It is the long-range plan of this project to study and understand changes in hepatic function following exposure to environmental agents emphasizing effects of hormonally active chemicals. These studies are defining the liver as a target organ for estrogens and androgens by characterizing cytosolic and nuclear steroid-binding proteins and correlating the presence of receptors with steroid-mediated induction or repression of protein synthesis. Some functional biochemical components of estrogen and androgen action in adult liver appear to be imprinted during a critical neonatal period by endogenous hormones. The imprinting of sex-dependent hepatic receptor synthesis is also evaluated in these studies. The pituitary-hypothalamic-hepatic-axis appears to regulate the ontogeny of hepatic metabolic steroid-binding proteins and the mechanisms involved are investigated in whole animal and culture systems. Environmental estrogens such as zearalenol mycotoxins, DES, and methoxychlor are assessed for estrogenic potency in liver.